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The character of alluvial gold deposits presents severe difficulties, and sometimes limitations, on the extent to which metallurgical efficiency can be measured. Very little monitoring of metallurgical performance is practised. An indication of performance is often extracted from the comparison of production to the estimate. This is a dubious practice. The recovery efficiency of conventional practices, viz sluices, tables and jigs, falls off sharply below 0.2 mm. Field evaluation procedures tend to simulate these conventional practices. Thus the presence of fine gold may not be detected, particularly if obscured by clay. There is increasing evidence that fine gold could, in places, be present in sufficient concentrations to be economic. Most gold in paleoplacers is finer than 0.1 mm. There are established practices elsewhere in the mineral industry that may physically recover gold down to 5 microns in size and which could find application for fine alluvial gold.

Jan 1, 1984

By A Deakin

It has been almost a decade since the release of the International Council of Mining and Metals (ICMM) Health and Safety Critical Control Management: Good Practice Guide (2015a). During this time the ICMM member companies, along with many others across industry, have been busy designing, deploying and enhancing their own critical control management (CCM) programs. So, what have we learnt? This paper discusses the scope, application and learnings from the implementation of CCM within the mining industry. What’s going well? What are the common challenges? What are the opportunities to strengthen the approach? What are the threats to successful implementation? The paper draws on the author’s experience as one of the key contributors to the development of the CCM Good Practice Guide and an adviser to many mining companies, including six of the ICMM members. The paper focuses on the practical (operational) application of CCM and the cycle of identifying, defining, implementing, verifying and improving critical controls at the frontline. The paper also includes a discussion on the safety performance of the ICMM member companies over the past decade and provides a recommendation for how CCM can be incorporated into a more proactive model to measure safety performance. The paper concludes with practical recommendations that mining companies, regardless of their CCM maturity, can consider as they look ahead. They are supplemented by three additional recommendations for consideration at the industry level.

Apr 16, 2024

By H Hoogvliet

The Goondicum Crater industrial minerals deposit is located about 30 km east of Monto, Central Queensland, Australia. Early exploration programs in the 1990s found alluvial ilmenite along the banks of the Burnett River. This mineralisation was traced upstream to the Goondicum Crater. The Goondicum Crater is a topographic feature centred on a roughly circular 6 km diameter layered gabbro complex. Significant ilmenite, apatite, titano-magnetite and feldspar mineralisation are present in a weathered horizon up to 25 m thick. After several drilling campaigns in the Crater and subsequent feasibility studies, the project was developed by Monto Minerals Ltd, an ASX listed company, in 2007. However, the project never achieved production performance expectations and ran out of commissioning funds. The company subsequently went into voluntary administration in August 2008.In 2009, the RMM Capital group, of Brisbane, took control of Monto Resources Pty Ltd, and renamed the company Belridge Enterprises Pty Ltd (Belridge). Belridge commissioned a redevelopment study aimed at recommencing mining and processing operations. As part of the redevelopment study the authors planned a drilling campaign, managed a quality control program and developed a block model. This paper describes the drilling program, analytical procedures, quality control procedures and the preparation of the block model.The block model for the resource estimate was created using 1 m high blocks, wireframes defining the main material types, and 2.5 m thick horizontal search ellipsoids with a radial pattern. The deposit was ‘flattened’ prior to modelling. To assist with the economic evaluation of the project, each block in the model was assigned a net dollar value based on economic parameters provided by Belridge, including anticipated revenues and costs. This modelling technique allowed for efficient investigation of various scenarios and was used extensively in the development and optimisation of the project’s financial model. At a zero net value per block, comparable to a break-even cut-off grade of four per cent ilmenite equivalent, the Indicated plus Measured resource is estimated at 51 Mt, averaging 4.1 per cent ilmenite, 1.9 per cent apatite and 2.5 per cent titano-magnetite.

Oct 5, 2011

By B Indraratna, A Dey

The surface geometry of a rock bolt plays a very important role in the rock/resin/bolt load transfer mechanism. Very little work has so far been reported on the influence of the bolt surface geometry on the bolt/resin interface failure mechanism. This paper examines the behaviour of bolt surface roughness under constant normal stiffness condition in the laboratory. To study the shear behaviour of the bolt/resin interface a series of shear tests with an initial normal stress between 0.1 to 7.5 MPa has been conducted on the flattened bolt surface of two most popular bolt types currently being used in Australia. Bolts with deeper ribs offered better shear resistance at low initial normal stress conditions whereas bolts with shallow and closer ribs offered better shear resistance at high normal stress conditions. The maximum dilation occurred at a shear displacement of 60 per cent of the rib spacing irrespective of the bolt type and depth of the rib.

Jan 1, 2000

By V S. Svinin, V V. Rybin, V A. Maltsev

In large-scale mining, large-sized intermediate pillars, or block-pillars, are generated on the horizon or between closely located mines. These pillars are mined under high rock pressure that results from the stress concentration zones superposition from closely located working excavations. This problem becomes much more complicated if high tectonic stresses occur in the rock mass inducing a rock-burst risk situation. Mining experience gained in mining seven block-pillars at three Khibiny mines in Russia under the geomechanical situation like that described aboveÆ is discussed in detail. It has been shown how safe mine of block-pillars depends on their width, location relative to significant geological failures and uncaved rocks of the hanging wall, the order of pillar recovery, and application of special measures for rock mass stress relieving. Basing on the analysis of the mining experience and special scientific researches, the basic principles are worked-out for safe block-pillar mining under rock-burst prone conditions.

Jan 1, 2000

By J O. Watson, V S. Vutukuri

This paper presents results of an investigation on acoustic emission characteristics of granite, sandstone and rock-like material in the unconfined compression and tensile tests. Both the acoustic emission signature and stress-stain curve are analysed in the experiments.The experimental results show that different acoustic emission characteristics are observed at different stress and deformation stages in unconfined compression and tensile testing. Extensive and unstable acoustic emission changes may be interpreted as indicating failure of the rock.

Jan 1, 1999

By K A. Heasley

The LaModel program was initially developed in 1993, and it is used to model the stresses and displacements in thin tabular deposits such as coal seams. It uses the displacement-discontinuity variation of the boundary-element method with a simplified laminated overburden model and because of this formulation, it is able to quickly and effectively analyse large areas of single- or multiple-seam mines. Over the last couple of decades, LaModel has been used by many mine engineers and researchers for improving pillar designs and mine safety, and it has been continually updated to add functionality and improve its ease of use and accuracy. The present LaModel can calculate seam displacements and overburden, multiple-seam and total seam stresses, pillar safety factors, energy values, roof-bending stresses, fault effects and surface subsidence. It can automatically generate the mine and overburden grids from AutoCAD drawings, and it includes wizards for automatically generating Bieniawski strength coal pillars, easily calibrating the overburden properties to observed abutment stresses and calibrating the gob material to expected gob loading. This paper will present the formulation and features of the modern LaModel program and demonstrate its utility with a multiple-seam case study from the rugged topography in Southern Appalachia.CITATION:Heasley, K A, 2014. LaModel – a program for coalmine modelling, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 409–414 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By Filigenzi M. T

Stresses around mine openings at depth can cause the surrounding rock to fail, releasing stored strain energy. When this happens, the rock may literally explode or `burst' into the opening without warning. As mining progresses deeper into the earth, the possibility of seismic events and rock bursts increases. Researchers at the US Bureau of Mines (USBM) are currently studying seismic activity in three underground hard-rock mines in the United States: the Homestake Mine, Lead, SD; the Lucky Friday Mine, Mullan, ID; and the Sunshine Mine, Kellogg, ID. Waveforms from seismic events are recorded by personal-computer-based hardware and software. This information is archived and transferred from the mine sites to the USBM via modem communication links. Then, using USBM-developed software, the events are analysed to determine various parameters, including magnitude, frequency, and location. In addition, researchers are modelling the deep levels of the Homestake Mine using a finite-element code. These models generate stress and displacement values for a given loading condition. By studying material properties, in situ stresses, and seismic activity along with actual scope sequencing, researchers can make correlations between stresses induced by mining and the frequency and magnitude of seismic events. Information on seismic events coupled with results from finite-element analyses have increased understanding of rock mass behavior and the mechanisms that may lead to rock bursts. Optimisation of slope sequencing designs as a result of these studies could reduce rock burst hazards.

Jan 1, 1995

By Gill L. F, Gleeson HB

This paper describes the development of a Computer Aided Design and Drafting based mine planning system in the State Electricity Com- mission of Victoria. The system combines a commercially available CADD system with a commercially available mining/geological package. The methodology used in the establishment of the combined system, the fea- tures of the system and the current status of development are discussed.

Jan 1, 1989

By H Barrie, L Ameglio

"Current methods for acid rock drainage (ARD) mitigation revolve around insulation of the waste from oxygen in the atmosphere with water and dry (soils and liners) covers. Both are of limited effectiveness and present significant drawbacks. Furthermore, while they reduce oxygen influx, they reduce but do not prevent ARD.The inert gas mixture (IGM) technology has been designed to overcome the deficiencies of gas transfer into tailings and waste rock materials across the surface and instead block oxidation by controlling the transfer of oxygen from the atmosphere. Inert gas is injected into the mine waste at low flow rates and the positive but low flow purges the oxygen that tends to diffuse into the sulfide waste across the surface. The positive flow of IGM compensates for inward oxygen diffusion and creates a pressure drop across the cover layer preventing inward diffusion of oxygen and, hence, acid generation.The IGM processes are evaluated in this paper: theoretically, with a review of the theory of ARD and the current state of knowledge about the performance of notably dry covers as atmospheric oxygen barriers via models to predict the performance of the IGM technique practically, with a bench-scaled experiment.The results demonstrate the effectiveness of IGM to prevent oxidation of sulfide minerals and ARD in waste rock. The laboratory experiments further identified key variables to be used to monitor performance and control efficiency of IGM, which is now awaiting field-scale application.The IGM technology is a patented process by Terraquest Technologies Ltd (Canada) in USA, Canada and Australia. The IGM technology can be cost-effectively manufactured on-site with commercially available compressors and gas filtration membranes. It is predicted that low-cost covers can then be utilised with IGM, which in turn lowers the overall capital costs of ARD mitigation.CITATION:Ameglio, L and Barrie, H, 2015. Acid rock drainage prevention using inert gas mixture technology, in Proceedings Tailings and Mine Waste Management for the 21st Century, pp 85–96 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jul 27, 2015

By S Kakara, A Kamaraj, S S. Varanasi, B V. R Mandalika, M B. Shaik

The properties of top slags play a very important role in secondary steelmaking. Fluxes should be chosen based on the ladle furnace (LF) slag requirements like viscosity, melting temperature, sulfide capacity, etc. CaF2 and CaO-Al2O3-based synthetic slags are the most used fluxes in secondary steelmaking to improve slag fluidity and interfacial chemical reactions. CaF2 is obsolete due to fluorine pollution and CaO-Al2O3 based slags have 40–50 wt per cent Al2O3 and 30–40 per cent CaO which is not beneficial for desulfurisation. Yet another drawback is that LF slag disintegrates into fine powder during cooling due to phase transformation C2S (2CaO.SiO2). Hence, there is a need for the development of low melting fluxes with high CaO content and the capability to prevent slag disintegration. The current work studied the effect of 0–9 wt per cent B2O3 on physico-chemical properties and characterisation of LF slags. X-ray diffraction (XRD) analyses were carried out to identify mineralogical phases present in slag and Fourier-transform infrared spectroscopy (FT-IR) analysis was done to understand the changes in bonds of B2O3 added LF slag. The characteristic temperature of slag was determined by a hemispherical method using high-temperature microscopy. Empirical models were used to calculate viscosity, break temperature, and sulfide capacity. FactSage™, ver 8.2 (by GTT-Technologies) simulations were carried out to find the equilibrium phase fractions and percentage of liquid slag at different temperatures. New phases such as Ca11B2Si4O22 and Ca2B3O5 were formed in LF slag with B2O3 addition. Based on the results, 0.5–1.0 wt per cent B2O3 was found to be sufficient to prevent C2S-driven disintegration of LF slag. Also, the melting temperature and viscosity of LF slag were reduced by adding 3–8 wt per cent B2O3 due to the formation of BO3 planar triangular structure and low melting eutectics in slag. Liquid slag started forming at a temperature as low as 800°C when B2O3 is >6 wt per cent. It was found that the sulfide capacity, viscosity, and break temperature of the slag decreased with increasing wt per cent B2O3. Based on the analysis carried out, B2O3 can be a promising fluxing material in secondary steelmaking, for improving the desulfurisation kinetics and valourisation potential of LF slag.

Aug 21, 2024

By E Amini, N Beaton

Application of ore pre-treatment technologies such as Grade Engineering and in-pit ore treatment require comprehensive analysis to show proven value is being generated by switching away from the current practices. Considering most mining operations last several decades; the pre-treatment technologies must be investigated over life of mine (LOM) to truly show value was generated or lost. Therefore, a value chain flowsheet model has been usually developed to run those analysis/simulations over LOM using a set of defined ore characteristics and the operating equipment capacities. The Integrated Extraction Simulator (IES) has been used for this type of LOM simulations as it has the necessary flexibility to accommodate the whole mining value chain flowsheet in one platform and provide essential computation power to run mass simulations for the given scenarios using the resource block model. This allows to forecast the value chain response over the LOM for all given scenarios in a feasible amount of time. The traditionally developed flowsheets for the analysis/simulations are usually limited to the mineral processing plant and were developed based on a single audit conducted on the plant in a very short time, e.g. several hours. The process plant is being operated with a certain ore at a certain condition during the short audits which would not reveal the true capacity of the operation equipment when ore characteristics changes. Therefore, it would be impossible to define the true capacity of the equipment and identify the constraints along the value chain. In this study, a methodology was developed to identify the constraints along the value chain and implement those in the IES flowsheet using process information. Also, the equipment models were fine-tuned to represent the true capacity of the equipment in the flowsheet using the same data set. The methodology was tested over five process plant in two operations and showed the performance forecast was significantly improved over the traditional methods being used so far. Then those high-fidelity flowsheets were used to evaluate the ore pre-treatment technologies proposed by the relevant resource company experts.

Nov 10, 2020

By E Amini, M Scott

Grade Engineering® involves the planning, integration and operation of coarse preconcentration techniques to reject uneconomic material as early as possible in the mining value chain to improve the quality of ore delivered to mineral processing activities. These preconcentration techniques include screening for natural and induced deportment of grade to finer size fractions during blasting and coarse breakage, sensor-based measurements of grade and mechanised sorting at particle or bulk scales and coarse gravity separation. Over the last decade, the Cooperative Research Centre for Optimising Resource Extraction (CRC ORE), with the support of its participants, has developed a framework for the holistic evaluation of economic and production impacts attributable to these preconcentration techniques. The framework combines the characterisation of preconcentration responses, geostatistical modelling, process modelling and simulation of downstream and upstream production impacts and the optimisation of strategic mine plans to quantify changes in net present value due to different preconcentration strategies. This framework has been applied to evaluate preconcentration techniques at numerous metalliferous operations and can also be used to quantify changes in the environmental metrics for energy, water and steel consumption and emission, tailings and waste rock production. This paper collates the results of these Grade Engineering® studies to show the range and magnitude of economic and environmental impacts attributable to preconcentration. The studies have shown that rejection of uneconomic material prior to mineral processing activities can have a pronounced improvement in energy, water and comminution steel productivity, emission intensity and the profitability of metalliferous mining.

Nov 10, 2020

By A R. Sale

This paper highlights two aspects of the mineral sands industry in Australia: the development of the industry from approximately 1870 through to 1980, and the author’s experience in the industry from 1966 to date.The first real heavy mineral (HM) mining in Australia started in 1870 with the mining of heavy mineral slicks on the beaches along the east coast of Australia. The real potential of Australian heavy minerals was however only realised in the 1920s with the first production of a heavy mineral concentrate that was shipped to Canada for processing. Post WW 11 and the Korean War, Australia was the largest producer of mineral sands products in the world as well as a significant developer of associated separation equipment and technology. The number of producing companies in the east coast peaked at 33 in 1957, was reduced to ten by 1965, and subsequently further reduced to five in 1980 as a result of potential mining areas being declared National Parks or Conservation Reserves. Today there is one company, Unimin Australia Pty Ltd (formally Consolidated Rutile Ltd) operating on the east coast. In contrast there were three companies on the west coast in 1965, four companies in 1980, and four companies today (albeit not the same companies).There have been considerable ups and downs for the industry in Australia, however world wide it was renowned in the past as being an industry that attracted numerous interesting and innovative characters that played a major role in developing it into the vibrant industry that it is today. This, given the current climate, is predicted to continue into the future.The author has been continuously involved in the industry for over 45 years from 1966, initially as an electrician at Consolidated Rutile Ltd culminating in the role of General Manager/President of Iluka Resources Limited USA, prior to his retirement in 2009. His exposure has been world wide and has covered all aspects of the industry but in the main focused on project development and operational areas. During this time there have been significant technological advances, yet to some extent the basic principles have not changed at all. Some of the most noteworthy advances include the development of the Wright Spiral in 1977, the development of the Reading High Intensity Wet Magnet (WHIMS), the rare earth magnets, the CRL floating thickener and the improvement of analytical techniques. From a safety, health and environmental perspective there has been significant advances that the industry has much to be proud of. These include wetland restoration both in Australia and in the US, the restoration of farmland in Virginia and Capel, and the re-establishment of native species, for example at Eneabba and Richards Bay to name but a few.

Oct 5, 2011

By J Visser

Dust mitigation has long been seen as nothing more than managing a nuisance issue, but the reality is that poor dust management can lead to one or more of the following negative consequences: an increased risk of safety incidents, lost revenue, reduced and possibly even lost licence to operate, regulatory intervention, high staff turnover and/or absenteeism and occupational health and safety (OH&S) issues. Dust mitigation and management is not a black art; rather it is a scientifically driven process that can provide an opportunity to increase profits, increase the companyÆs status as an excellent corporate citizen, enhance staff retention and reduce the safety risk profile of the operation.The way to achieve success in dust mitigation and control is to apply the scientific method to each problem that can arise and plague any operation by using current industry best practice. This method of dust problem-solving can be applied to dust issues arising from specific dust sources and locations. The dust sources can include wind impacting on stockpiles, open areas, tailings storage facilities, moving train and truck loads, vehicular traffic on roads, the operation of shovels, front end loaders, draglines and other equipment, as well as ore movement on conveyors.The solutions will come from a combination of deployment of dust collection equipment, dust and moisture monitoring equipment, the appropriate application of water and chemicals, the introduction and maintenance of appropriate barriers and the use of predictive data from local and public weather stations. The paradigm shift required is to view dust mitigation as one aspect of normal operational practice, not a ænice to haveÆ or æunnecessary expenseÆ as most operators currently view it. This attitude is becoming more important as more and more local communities oppose the development of mines. One of the reasons for this local opposition is the inevitable dusty environment that is usually associated with mining.Dust mitigation is not a significant expense if correctly designed and included into the system, either as part of the original design of the operation or as a brownfield installation after the fact. Indeed, there is always a loss of revenue associated with dustiness resulting from ore movement and avoiding this goes a long way to paying for any associated dust mitigating costs.CITATION:Visser, J, 2013. Dust mitigation - changing the paradigm, in Proceedings Iron Ore 2013 , pp 27-38 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By P Dowd, R Jeuken, C Xu

In Australian coalmines there are a number of coal quality parameters that are measured by analysing samples from boreholes. The data points are used to generate spatial models of these parameters, typically using inverse distance as an interpolation method. Numerous additional boreholes are drilled which have geophysical logs measured downhole but from which no coal quality samples are taken. Full suites of coal quality analyses are expensive and time consuming to drill and sample. If geophysical proxies for coal quality could be used, this would greatly improve the accuracy of the resource estimation without additional cost.This paper examines two of the most important coal quality parameters – ash and volatile matter – and assesses the results of a number of geostatistical interpolation methods. The aim is to improve the accuracy of the interpolated models. Auxiliary variables from geophysical logs are also trialled to improve the estimation.A multivariate analysis of ash, volatile matter and several auxiliary variables of a selected coal seam was undertaken in a spatial context, using variography. This was used to construct a model of co-regionalisation that relates all of the variables as manifestations of an underlying geological theme.The traditional inverse distance interpolation approach was compared to ordinary kriging, universal kriging, co-kriging, regression kriging and kriging with external drift approaches. The relative merits of the six interpolation methods were compared by removing all points, one at a time and estimating at the thus known location. The mean error and the root mean square error were evaluated as a measure of bias and precision.This paper demonstrates that there is significant opportunity to improve the estimations of coal quality when using kriging with external drift. For example, the results show that when using the depth of a sample as an external drift variable there is a significant improvement in the accuracy of estimation for volatile matter. Furthermore, when using borehole wireline density logs as an auxiliary variable for ash content, there is improvement in the estimation of the in situ ash. The underpinning reasons for this are discussed in the context of the underlying geology and the physical properties of the coal. These findings hold promise for utilising cheaper proxies for coal quality parameters to dramatically improve data density and the quality of estimations.CITATION:Jeuken, R, Xu, C and Dowd, P, 2017. Improving coal quality estimations using geostatistics and auxiliary variables, in Proceedings Tenth International Mining Geology Conference 2017, pp 157–168 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 20, 2017

By J Mar·n, R Anderson, S Strohma, R Harvey

Xstrata is the operator of both Minera Alumbrera Ltd (50 per cent Xstrata, 50 per cent Wheaton River) and Ernest Henry Mining Pty Ltd, (99.99 per cent Xstrata), both copper-gold deposits, using conventional SAG/ball milling at current capacities of 36 Mt/yr and 10.3 Mt/yr respectively. Alumbrera is located in Catamarca Province, in the north west of Argentina. Ernest Henry is located in Cloncurry, north west Queensland, Australia. Both operations started in late 1997, with commercial production achieved in early 1998. Different designs and equipment are in use for both operations, however the evolution of SAG milling performance, although logically related to their specific features, reflect similar trends of consistent increases in throughput. This paper will discuss the main changes to the SAG mill liners in both operations and the results achieved to date. A summary of the operating strategies will be included.

Jan 1, 2003

THE paper is principally eoncerncd with experimental work carried out the author whilst a number of the metallurgical staff at the Cockle Creek works. The metallurgical has been discussed sufficiently for the reader to follow the course of the experiments but the actual plant has only been described in so far as it effected metallurgical treatment, since the arrangement of such a smelter is a matter of common knowledge.The lead-roasting plant consisted of Godfrey roaster, Dwight-Lloyd maehines and Huntingdon-Heberlein pots. The usual treatment was in the Godfrey furnaces, followed by sintering in the Huntingdon- Heberlein pots. The paper is divided into two parts in the Godfrey furnaces and Huntingdon-Heberlein pots. An account of experiments on the utilization of the hood gases from the Huntingdon-Heberlein pots for acid making...

Jan 1, 1924

This paper addresses, in particular, the influence of winding depth on the selection of head ropes for Koepe winders. Because this is just one aspect of winder design that affects the operational safety of the winding system, the paper starts by considering all the issues governing the life and safety of the winding ropes. Regulations from a variety of countries are reviewed and comparisons of the legislated rope factors of safety and their variation with winding depth are made. This is followed by a discussion of the typical observed mode of in-service deterioration of Koepe head ropes. This mode of deterioration is due to fatigue and is influenced by the load range occurring in the ropes. Parameters contributing to load range are discussed and the influence of winding depth is highlighted. Lessons learned from early experience with very deep Koepe winders in South Africa are recalled. Predictions of load range as a function of depth are made, from which general rope life predictions are made for ropes selected by conventional national factor of safety requirements. This is illustrated in graphs comparing rope life as a function of depth. Typically a reducing life with depth is predicted. A rope selection strategy is advocated, which is based on achieving a constant rope life irrespective of the depth of wind. A new factor of safety (or rope design factor) equation is prepared that has the trend of increasing with depth. This proposed equation is compared with other published proposals that promote an increasing rope factor of safety with depth. It is shown that smoother winder drive controls enhance winding rope life and this improvement is quantified. The paper concludes by pointing out the consistency in predicted and observed life of winding ropes selected in accordance with legislated factor of safety approaches. It recommends the adoption of a new rope design factor equation for rope selection, to be used in conjunction with appropriate codes of practice for winding rope condition assessment and for the design, installation, operation, maintenance and testing of Koepe winders. The new rope design factor equation approaches a limiting economic depth of wind at shallower depths than the existing Koepe factor of safety approaches. However these older approaches æbuild-inÆ a reducing rope life with depth. The new rope design factor is therefore a more consistent way to select Koepe ropes and to evaluate economic trade-offs between Koepe and conventional double-drum or Blair winding systems.

Jan 1, 2005

By Forssberg E

This paper presents the experimental results on the effects of slurry Theology on ultra-fine grinding by a stirred ball mill. The amount of dispersant, slurry density and the particle size were selected as the parameters. The viscosity of dolomite-water slurry was measured by rotational viscometers. It was found that by adding enough dispersant, the effect of particle size from 1 to 10 pm on the slurry theology could be eliminated, but a strong effect of slurry density (tested for a range of 65 to 75 wt per cent) remained. The use of dispersant transformed the slurry from Bingham plastic flow to dilatant flow, which reduced the yield stress to zero, but increased the viscosity at higher shear rates. During the milling process, the viscosity was stable. The yield stress, however, increased suddenly from zero after a certain milling time. The mill operation stopped at the point where the yield stress increased due to poor slurry fluidity. The milling efficiency was found to be higher at a lower amount of dispersant addition or a lower slurry density within the experimental limits.

Jan 1, 1993